Comfort

As expected, the Adidas Boost midsole delivered a level of comfort underfoot that others couldn’t. Definitely being one of the softer shoes tested, the UltraBOOST ST offered a heaping 32 mm of cushioning under the heel and 24 mm beneath the forefoot. All of our testers agreed the UltraBOOST ST had the best level of cushioning of all the shoes tested. The upper was designed with Primeknit, a knit-like fabric that is soft and offers plenty of room, but seemed a bit thick and lacked structure.

Fit

Similar to its predecessor, the new UltraBOOST ST fits extremely large in both width and length. Enough so that going down a half size may be worth looking into. One tester described her experience in the UltraBOOST ST as “running in Jello.” Excess room in the upper created an insecure feeling. The knit upper was excessively roomy and did not provide enough structure to control internal foot movement. Flexible plastic was placed along the heel counter to assist in guiding the foot through the gait.

Responsiveness 

Typically Adidas’ Boost midsole offers excellent responsiveness, but that was not the case with the new UltraBOOST ST. The shoe was too soft, to the point that it felt mushy. Downward energy in each foot plant seems to sink into the midsole and stop, with very little rebound. This mushy underfoot feeling coupled with a lack of control caused by the roomy upper crippled the overall performance of the shoe.

Speed

This year’s UltraBOOST ST added roughly an additional 15 grams over its predecessor, making it one of the slowest shoes tested in the comfort category this season. It was the heaviest shoe of the test and ran like it. Getting the shoe to respond quickly felt like a chore, mostly due to the heavy weight and ill fitting upper. It felt like the shoe was controlling you, not the other way around.

Ride Quality

One word summed up the ride of the UltraBOOST ST: Soft. Despite offering mild stability, the Adidas UltraBOOST ST rides more like a neutral shoe. There was a smooth transition through the gait without the detection of stiff medial or arch support, prompting one tester to question if it should be advertised as a stability shoe at all.